Abnormal superior popliteomeniscal fascicle and posterior pericapsular edema: Indirect MR imaging signs of a lateral meniscal tear

OBJECTIVE. Because MR diagnosis of lateral meniscal tears can be difficult, indirect signs may be useful when a tear is suspected. We studied whether an abnormality of the superior popliteomeniscal fascicle or pericapsular ed ema was associated with lateral meniscal tears and thus may be an indirect MR imaging sign of a lateral meniscal tear. MATERIALS AND METHODS. We identified 59 consecutive patients who underwent both knee MR imaging examinations and knee arthroscopy. Thirty patients had lateral meniscal tears, and 29 had intact lateral menisci. We reviewed pai red sagittal proton density- and T2-weighted MR images from these 59 patien ts for abnormal superior popliteomeniscal fascicles and edema surrounding t he posterolateral capsule. RESULTS. The superior popliteomeniscal fascicles were abnormal in nine of t he 30 patients with torn lateral menisci but were normal in all 29 patients with intact menisci (p = 0.001). Abnormal fascicles were apparent only whe n the lateral meniscal tear involved the posterior horn. Posterior pericaps ular edema was seen in 10 patients with a torn posterior horn and in one pa tient with an anterior horn tear of the lateral meniscus, but in only two p atients with intact menisci (p = 0.006). CONCLUSION. The presence of superior popliteomeniscal fascicle abnormalitie s and of posterior pericapsular edema is significantly associated with a te ar of the lateral meniscus, most commonly in the posterior hem. Noting the presence of these findings may help improve the accuracy of MR diagnosis of lateral meniscal tears.